HiRISE

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A worker prepares HiRISE before it is shipped for attachment to the spacecraft

The High Resolution Imaging Science Experiment camera is a camera onboard the Mars Reconnaissance Orbiter. The $40 million dollar (US) instrument was built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp.. It consists of a 0.5 meter reflecting telescope, the largest of any deep space mission, which allows it to take pictures with resolutions up to 0.3 m resolving objects about a meter across, or the size of a beachball.

1 History
2 Purpose
3 Design
4 Footnotes
5 External links

[edit] History

Crop of first image of Mars from the HiRISE camera

In the late 1980s, Alan Delamere of Ball Aerospace began planning the kind of high-resolution imaging needed to support sample return and surface exploration of Mars. In early 2001 he teamed up with Alfred McEwen of the University of Arizona to propose such a camera for MRO, and NASA formally accepted it November 9, 2001.^[1]

Ball Aerospace was given the responsibility to build the camera and they delivered HiRISE to NASA on December 6, 2004, for integration with the rest of the spacecraft.^[2] It was prepared for launch onboard the MRO on August 12, 2005, to the cheers of the HiRISE team who were present. ^[3]

Artist's redition of HiRISE at Mars

During the cruise phase of MRO, HiRISE took several calibration shots including several of the Moon and the Jewel Box cluster. These images helped to calibrate the camera and prepare it for taking pictures of Mars.

On March 10, 2006, MRO achieved Martian orbit and primed HiRISE to acquire some initial images of Mars.^[4] The instrument had two opportunities to take pictures of Mars (the first was on March 24, 2006) before MRO entered aerobraking, during which time the camera was turned off for six months.^[5] It was turned on successfully September 27, and took its first high-resolution pictures of Mars September 29.

On October 6, 2006 HiRISE took the first image of Victoria Crater, a site which is also under study by the rover Opportunity.^[6]

In February 2007 seven detectors showed signs of degradation, with one IR channel almost completely degraded, and one other showing advanced signs of degredation. The problems appear to disappear when higher temperatures are used to take pictures with the camera.^[7] As of March the degradation appeared to have stabilized, but the underlying cause remained unknown.^[8]

[edit] Purpose

Comparison of resolution of MRO HiRISE camera with predecessor, the MOC aboard MGS

The HiRISE camera is designed to view surface features of Mars in greater detail than has previously been possible. ^[9] This allows for the study of the age of Martian features, looking for landing sites for future Mars landers, and in general, seeing the Martian surface in far greater detail than has previously been done from orbit. By doing so, it is allowing better studies of Martian channels and valleys, volcanic landforms, possible former lakes and oceans, and other surface landforms as they exist on the Martian surface. ^[10]

The general public will soon be allowed to request sites to take pictures of Mars with the HiRISE camera. For this reason, and due to the unprecedented access of pictures to the general public, shortly after they have been received and processed, the camera has taken the philosophy "The People's Camera". ^[11]

[edit] Design

HiRISE was designed to be a High Resolution camera from the beginning. It consists of a large mirror, as well as a large CCD camera. Because of this, it achieves a resolution of 1 microradian, or 0.3 meter at a height of 300 km. (For comparison purposes, satellite images of Earth are generally available to a resolution of 0.1 meter, and satellite images on Google Maps are available to 1 meter.^[12]) It can image in three color bands, 400-600 nm (blue-green or B-G), 550-850 nm (red) and 800-1,000 nm (near infrared or NIR).^[13]

Red color images are at 20,264 pixels wide (6 km in a 300 km orbit), and Green-Blue and NIR are at 4,048 pixels wide (1.2 km). HiRISE's onboard computer reads out these lines in time with the orbiter's ground speed, meaning the images are potentially unlimited in height. Practically this is limited by the onboard computer's 28 Gb memory capacity. The nominal maximum resolution of red images is 20,000 × 40,000 pixels, or 800 megapixels and 4,000 × 40,000 pixels (160 megapixels) for the narrower images of the B-G and NIR bands. A single uncompressed image uses 16.4 Gb. However, these images are transmitted compressed, at a total size of 5 Gigabits. These images are released to the general public on the HiRISE website via a new format called JPEG 2000. ^[14]^,^[15]

To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which the topography can be measured to an accuracy of 0.25 meter.